Transcript Lecture 5 Transmitters and receptors lecture 2015

6.1 Examples of small-molecule and peptide neurotransmitters. (Part 1)
6.1 Examples of small-molecule and peptide neurotransmitters. (Part 2)
6.1 Examples of small-molecule and peptide neurotransmitters. (Part 3)
6.1 Examples of small-molecule and peptide neurotransmitters. (Part 4)
6.1 Examples of small-molecule and peptide neurotransmitters. (Part 5)
6.15 Neuropeptides vary in length, but usually contain between 3 and 36 amino acids.
5.5 Metabolism of small-molecule and peptide transmitters. (Part 1)
5.5 Metabolism of small-molecule and peptide transmitters. (Part 3)
5.5 Metabolism of small-molecule and peptide transmitters. (Part 4)
5.12 Differential release of neuropeptide and small-molecule co-transmitters.
6.2 Acetylcholine metabolism in cholinergic nerve terminals.
6.6 Glutamate synthesis and cycling between neurons and glia.
6.8 Synthesis, release, and reuptake of the neurotransmitters GABA and glycine. (Part 2)
6.8 Synthesis, release, and reuptake of the neurotransmitters GABA and glycine. (Part 1)
Figure 6.10 The biosynthetic pathway for the catecholamine neurotransmitters
Neurotransmitters and transporters: Dopamine factoids
•Dopamine is believed to be involved in motivation, reward, and reinforcement
and many drugs of abuse affect dopaminergic synapses. Dopamine action in
the synaptic cleft is terminated by the reuptake of dopamine into the nerve
terminal or neighboring glia by a Na+ dependent dopamine transporter (DAT).
Cocaine exerts its effects by binding to and inhibiting DAT which causes an
increase in the amount of dopamine in the synaptic cleft.
•Amphetamine, another addictive drug, also inhibits DAT as well as the
transporter for norepinephrine.
•The two major enzymes involved in the breakdown of dopamine are
monoamine oxidase (MAO) and catechol O-methyltransferase (COMT).
Inhibitors of these enzymes such as phenelzine and tranylcypromine are used
clinically as antidepressants.
6.18 Synthesis, release, and termination of NO.
Box F Marijuana and the Brain (Part 1)
Box F Marijuana and the Brain (Part 2)
5.22 A neurotransmitter can affect a postsynaptic cell via two types of receptor proteins. (Part 2)
Figure 7.5 Types of GTP-binding proteins (Part 1)
Figure 7.6 Effector pathways associated with G-protein-coupled receptors
Figure 6.4 Muscarinic and other metabotropic receptors
5.22 A neurotransmitter can affect a postsynaptic cell via two types of receptor proteins. (Part 1)
6.4 The general architecture of ligand-gated receptors. (Part 1)
The families of ligand-gated receptors.
Glutamate receptor subtypes are named after the agonists that activate them:
AMPA: a-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate
NMDA: N-methyl-D-aspartate
Kainate: Kainic acid
Most central synapses have both AMPA and NMDA receptors
6.3 The structure of the nACh receptor/channel. (Part 2)
6.9 Ionotropic GABA receptors. (Part 2)
GABA acting on GABAARs usually hyperpolarizes cells because ECl
is more negative than the resting potential, so Cl- flows into the
cell. In some cases GABA can evoke depolarization instead of
hyperpolarization in neurons. This can occur if the chloride
equilibrium potential (ECl) is positive to the resting potential.
What controls where ECl is? It depends on intracellular chloride
concentration, which appears to be regulated primarily by two
transporters, an Na-K-Cl cotransporter (NKCC) that normally
accumulates chloride and a K-Cl cotransporter (KCC) that
normally extrudes chloride (for review, see Russell, 2000).
Certain neurons and epithelial cells with ECl positive to the
resting potential express NKCC, whereas neurons with an ECl
negative to the resting potential express KCC2 (the neuronspecific isoform).
6.7 NMDA and AMPA/kainate receptors. (Part 1)
Figure 6.6 Postsynaptic responses mediated by ionotropic glutamate receptors (Part 2)
Figure 5.17 Activation of ACh receptors at neuromuscular synapses
Figure 5.18 The influence of the postsynaptic membrane potential on end plate currents
EPC=g(Vm-Erev)
5.16 The influence of the postsynaptic membrane potential on end plate currents. (Part 3)
Lower external Na+
Higher external K+
5.17 The effect of ion channel selectivity on the reversal potential. (Part 1)
EPC=g(Vmem – Erev)
5.17 The effect of ion channel selectivity on the reversal potential. (Part 2)
5.18 Na+ and K+ movements during EPCs and EPPs. (Part 1)
5.18 Na+ and K+ movements during EPCs and EPPs. (Part 2)
5.18 Na+ and K+ movements during EPCs and EPPs. (Part 3)
5.18 Na+ and K+ movements during EPCs and EPPs. (Part 4)
5.19 Reversal and threshold potentials determine postsynaptic excitation and inhibition. (Part 1)
5.19 Reversal and threshold potentials determine postsynaptic excitation and inhibition. (Part 2)
5.20 Summation of postsynaptic potentials. (Part 1)
Figure 5.22 Summation of postsynaptic potentials (Part 2)
Unusual neurotransmitters:
Adenosine triphosphate (ATP)
ATP is made from adenosine
and packed into large dense
core or small synaptic type
vesicles. ATP is released along
with another transmitter, or
by itself. After release, ATPase
and other enzymes break it
down and adenosine can be
taken up again.
In this example, ATP, norepinephrine, and neuropeptide Y (NPY) exert complex effects on
smooth muscle. Stimulation of a sympathetic neuron causes three phases of contraction of a
vascular smooth muscle cell. Phase 1-ATP binds to a P2X purinoceptor (a ligand-gated cation
channel) leading to depolarization, activation of voltage-gated Ca2+ channels, increased
[Ca2+]i, and the rapid phase of contraction. Phase 2-norepinephrine binds to an alpha 1adrenergic receptor, which, via a Gq/PLC/IP3 cascade, leads to Ca2+ release from internal
stores and the second phase of contraction. Phase 3-when present, NPY binds to a Y1
receptor and somehow causes an increase in [Ca2+]i and thus produces the slowest phase of
contraction.
ER, endoplasmic reticulum; IP3 inositol 1,4,5-triphosphate; PLC, phospolipase C.
© 2005 Elsevier
Unusual neurotransmitters: NO
Nitric oxide is made from
L-arginine and a cofactor, citrullline
by the enzyme nitric oxide synthase.
Stimulation of a postganglionic
parasympathetic neuron can cause
complex effects on vascular smooth
muscle cell. The first phase in this
example is mediated by both nitric
oxide (NO) and acetylcholine. The
neuron releases NO, which diffuses
to the smooth muscle cell.
In addition, acetylcholine (ACh) binds to M3 muscarinic receptors(G-protein linked) on
endothelial cells, leading to production of NO, which also diffuses to the smooth
muscle cell. Both sources of NO raise [cGMP]i in the smooth muscle cell and
contribute to the first phase of relaxation. In the second phase, which tends to occur
more with prolonged or intense stimulation, the neuropeptide VIP (or a related
peptide) binds to receptors on the smooth muscle cell and causes a delayed
relaxation via an increase in [cAMP]i or a decrease in [Ca2+ ]i. cGMP, cyclic guanosine
monophosphate.
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© 2005 Elsevier